Utilizing our model for pre-hepatic insulin production and for hepatic insulin extraction patients with unique problems in the glucose/insulin axis are investigated; this includes iron-storage diabetes, Addison's disease, insulinomas, etc. The study was expanded to include a separate protocol (78-19a) for the use of biosynthetic human C-peptide disposal in these same subjects allowing precise calculation of prehepatic insulin production rates. We have also initiated study of non-steady nitrate glucose kinetics in man.